[SPARK-4574][SQL] Adding support for defining schema in foreign DDL commands.

sql/core/src/main/scala/org/apache/spark/sql/json/JSONRelation.scala

@@ -18,31 +18,48 @@
 package org.apache.spark.sql.json
 
 import org.apache.spark.sql.SQLContext
+import org.apache.spark.sql.catalyst.types.StructType
 import org.apache.spark.sql.sources._
 
-private[sql] class DefaultSource extends RelationProvider {
-  /** Returns a new base relation with the given parameters. */
+private[sql] class DefaultSource extends RelationProvider with SchemaRelationProvider {
+
+  /** Returns a new base relation with the parameters. */
   override def createRelation(
       sqlContext: SQLContext,
       parameters: Map[String, String]): BaseRelation = {
     val fileName = parameters.getOrElse("path", sys.error("Option 'path' not specified"))
     val samplingRatio = parameters.get("samplingRatio").map(_.toDouble).getOrElse(1.0)
 
-    JSONRelation(fileName, samplingRatio)(sqlContext)
+    JSONRelation(fileName, samplingRatio, None)(sqlContext)
+  }
+
+  /** Returns a new base relation with the given schema and parameters. */
+  override def createRelation(
+      sqlContext: SQLContext,
+      parameters: Map[String, String],
+      schema: StructType): BaseRelation = {
+    val fileName = parameters.getOrElse("path", sys.error("Option 'path' not specified"))
+    val samplingRatio = parameters.get("samplingRatio").map(_.toDouble).getOrElse(1.0)
+
+    JSONRelation(fileName, samplingRatio, Some(schema))(sqlContext)
   }
 }
 
-private[sql] case class JSONRelation(fileName: String, samplingRatio: Double)(
+private[sql] case class JSONRelation(
+    fileName: String,
+    samplingRatio: Double,
+    userSpecifiedSchema: Option[StructType])(
     @transient val sqlContext: SQLContext)
   extends TableScan {
 
   private def baseRDD = sqlContext.sparkContext.textFile(fileName)
 
-  override val schema =
-    JsonRDD.inferSchema(
-      baseRDD,
-      samplingRatio,
-      sqlContext.columnNameOfCorruptRecord)
+  override val schema = userSpecifiedSchema.getOrElse(
+    JsonRDD.nullTypeToStringType(
+      JsonRDD.inferSchema(
+        baseRDD,
+        samplingRatio,
+        sqlContext.columnNameOfCorruptRecord)))
 
   override def buildScan() =
     JsonRDD.jsonStringToRow(baseRDD, schema, sqlContext.columnNameOfCorruptRecord)

sql/core/src/main/scala/org/apache/spark/sql/sources/ddl.scala

@@ -17,16 +17,15 @@
 
 package org.apache.spark.sql.sources
 
-import org.apache.spark.Logging
-import org.apache.spark.sql.SQLContext
-import org.apache.spark.sql.execution.RunnableCommand
-import org.apache.spark.util.Utils
-
 import scala.language.implicitConversions
-import scala.util.parsing.combinator.lexical.StdLexical
 import scala.util.parsing.combinator.syntactical.StandardTokenParsers
 import scala.util.parsing.combinator.PackratParsers
 
+import org.apache.spark.Logging
+import org.apache.spark.sql.SQLContext
+import org.apache.spark.sql.catalyst.types._
+import org.apache.spark.sql.execution.RunnableCommand
+import org.apache.spark.util.Utils
 import org.apache.spark.sql.catalyst.plans.logical._
 import org.apache.spark.sql.catalyst.SqlLexical
 
@@ -44,6 +43,14 @@ private[sql] class DDLParser extends StandardTokenParsers with PackratParsers wi
     }
   }
 
+  def parseType(input: String): DataType = {
+    phrase(dataType)(new lexical.Scanner(input)) match {
+      case Success(r, x) => r
+      case x =>
+        sys.error(s"Unsupported dataType: $x")
+    }
+  }
+
   protected case class Keyword(str: String)
 
   protected implicit def asParser(k: Keyword): Parser[String] =
@@ -55,6 +62,24 @@ private[sql] class DDLParser extends StandardTokenParsers with PackratParsers wi
   protected val USING = Keyword("USING")
   protected val OPTIONS = Keyword("OPTIONS")
 
+  // Data types.
+  protected val STRING = Keyword("STRING")
+  protected val BINARY = Keyword("BINARY")
+  protected val BOOLEAN = Keyword("BOOLEAN")
+  protected val TINYINT = Keyword("TINYINT")
+  protected val SMALLINT = Keyword("SMALLINT")
+  protected val INT = Keyword("INT")
+  protected val BIGINT = Keyword("BIGINT")
+  protected val FLOAT = Keyword("FLOAT")
+  protected val DOUBLE = Keyword("DOUBLE")
+  protected val DECIMAL = Keyword("DECIMAL")
+  protected val DATE = Keyword("DATE")
+  protected val TIMESTAMP = Keyword("TIMESTAMP")
+  protected val VARCHAR = Keyword("VARCHAR")
+  protected val ARRAY = Keyword("ARRAY")
+  protected val MAP = Keyword("MAP")
+  protected val STRUCT = Keyword("STRUCT")
+
   // Use reflection to find the reserved words defined in this class.
   protected val reservedWords =
     this.getClass
@@ -67,26 +92,92 @@ private[sql] class DDLParser extends StandardTokenParsers with PackratParsers wi
   protected lazy val ddl: Parser[LogicalPlan] = createTable
 
   /**
-   * CREATE TEMPORARY TABLE avroTable
+   * `CREATE TEMPORARY TABLE avroTable
    * USING org.apache.spark.sql.avro
-   * OPTIONS (path "../hive/src/test/resources/data/files/episodes.avro")
+   * OPTIONS (path "../hive/src/test/resources/data/files/episodes.avro")`
+   * or
+   * `CREATE TEMPORARY TABLE avroTable(intField int, stringField string...)
+   * USING org.apache.spark.sql.avro
+   * OPTIONS (path "../hive/src/test/resources/data/files/episodes.avro")`
    */
   protected lazy val createTable: Parser[LogicalPlan] =
-    CREATE ~ TEMPORARY ~ TABLE ~> ident ~ (USING ~> className) ~ (OPTIONS ~> options) ^^ {
-      case tableName ~ provider ~ opts =>
-        CreateTableUsing(tableName, provider, opts)
+  (
+    CREATE ~ TEMPORARY ~ TABLE ~> ident
+      ~ (tableCols).? ~ (USING ~> className) ~ (OPTIONS ~> options) ^^ {
+      case tableName ~ columns ~ provider ~ opts =>
+        val userSpecifiedSchema = columns.flatMap(fields => Some(StructType(fields)))
+        CreateTableUsing(tableName, userSpecifiedSchema, provider, opts)
     }
+  )
+
+  protected lazy val tableCols: Parser[Seq[StructField]] =  "(" ~> repsep(column, ",") <~ ")"
 
   protected lazy val options: Parser[Map[String, String]] =
     "(" ~> repsep(pair, ",") <~ ")" ^^ { case s: Seq[(String, String)] => s.toMap }
 
   protected lazy val className: Parser[String] = repsep(ident, ".") ^^ { case s => s.mkString(".")}
 
   protected lazy val pair: Parser[(String, String)] = ident ~ stringLit ^^ { case k ~ v => (k,v) }
+
+  protected lazy val column: Parser[StructField] =
+    ident ~ dataType ^^ { case columnName ~ typ =>
+      StructField(columnName, typ)
+    }
+
+  protected lazy val primitiveType: Parser[DataType] =
+    STRING ^^^ StringType |
+    BINARY ^^^ BinaryType |
+    BOOLEAN ^^^ BooleanType |
+    TINYINT ^^^ ByteType |
+    SMALLINT ^^^ ShortType |
+    INT ^^^ IntegerType |
+    BIGINT ^^^ LongType |
+    FLOAT ^^^ FloatType |
+    DOUBLE ^^^ DoubleType |
+    fixedDecimalType |                   // decimal with precision/scale
+    DECIMAL ^^^ DecimalType.Unlimited |  // decimal with no precision/scale
+    DATE ^^^ DateType |
+    TIMESTAMP ^^^ TimestampType |
+    VARCHAR ~ "(" ~ numericLit ~ ")" ^^^ StringType
+
+  protected lazy val fixedDecimalType: Parser[DataType] =
+    (DECIMAL ~ "(" ~> numericLit) ~ ("," ~> numericLit <~ ")") ^^ {
+      case precision ~ scale => DecimalType(precision.toInt, scale.toInt)
+    }
+
+  protected lazy val arrayType: Parser[DataType] =
+    ARRAY ~> "<" ~> dataType <~ ">" ^^ {
+      case tpe => ArrayType(tpe)
+    }
+
+  protected lazy val mapType: Parser[DataType] =
+    MAP ~> "<" ~> dataType ~ "," ~ dataType <~ ">" ^^ {
+      case t1 ~ _ ~ t2 => MapType(t1, t2)
+    }
+
+  protected lazy val structField: Parser[StructField] =
+    ident ~ ":" ~ dataType ^^ {
+      case fieldName ~ _ ~ tpe => StructField(fieldName, tpe, nullable = true)
+    }
+
+  protected lazy val structType: Parser[DataType] =
+    (STRUCT ~> "<" ~> repsep(structField, ",") <~ ">" ^^ {
+    case fields => new StructType(fields)
+    }) |
+    (STRUCT ~> "<>" ^^ {
+      case fields => new StructType(Nil)
+    })
+
+  private[sql] lazy val dataType: Parser[DataType] =
+    arrayType |
+    mapType |
+    structType |
+    primitiveType
 }
 
 private[sql] case class CreateTableUsing(
     tableName: String,
+    userSpecifiedSchema: Option[StructType],
     provider: String,
     options: Map[String, String]) extends RunnableCommand {
 
@@ -99,8 +190,29 @@ private[sql] case class CreateTableUsing(
             sys.error(s"Failed to load class for data source: $provider")
         }
     }
-    val dataSource = clazz.newInstance().asInstanceOf[org.apache.spark.sql.sources.RelationProvider]
-    val relation = dataSource.createRelation(sqlContext, new CaseInsensitiveMap(options))
+
+    val relation = userSpecifiedSchema match {
+      case Some(schema: StructType) => {
+        clazz.newInstance match {
+          case dataSource: org.apache.spark.sql.sources.SchemaRelationProvider =>
+            dataSource
+              .asInstanceOf[org.apache.spark.sql.sources.SchemaRelationProvider]
+              .createRelation(sqlContext, new CaseInsensitiveMap(options), schema)
+          case _ =>
+            sys.error(s"${clazz.getCanonicalName} should extend SchemaRelationProvider.")
+        }
+      }
+      case None => {
+        clazz.newInstance match {
+          case dataSource: org.apache.spark.sql.sources.RelationProvider  =>
+            dataSource
+              .asInstanceOf[org.apache.spark.sql.sources.RelationProvider]
+              .createRelation(sqlContext, new CaseInsensitiveMap(options))
+          case _ =>
+            sys.error(s"${clazz.getCanonicalName} should extend RelationProvider.")
+        }
+      }
+    }
 
     sqlContext.baseRelationToSchemaRDD(relation).registerTempTable(tableName)
     Seq.empty

sql/core/src/main/scala/org/apache/spark/sql/sources/interfaces.scala

@@ -18,7 +18,7 @@ package org.apache.spark.sql.sources
 
 import org.apache.spark.annotation.{Experimental, DeveloperApi}
 import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.{SQLConf, Row, SQLContext, StructType}
+import org.apache.spark.sql.{Row, SQLContext, StructType}
 import org.apache.spark.sql.catalyst.expressions.{Expression, Attribute}
 
 /**
@@ -44,6 +44,33 @@ trait RelationProvider {
   def createRelation(sqlContext: SQLContext, parameters: Map[String, String]): BaseRelation
 }
 
+/**
+ * ::DeveloperApi::
+ * Implemented by objects that produce relations for a specific kind of data source.  When
+ * Spark SQL is given a DDL operation with
+ * 1. USING clause: to specify the implemented SchemaRelationProvider
+ * 2. User defined schema: users can define schema optionally when create table
+ *
+ * Users may specify the fully qualified class name of a given data source.  When that class is
+ * not found Spark SQL will append the class name `DefaultSource` to the path, allowing for
+ * less verbose invocation.  For example, 'org.apache.spark.sql.json' would resolve to the
+ * data source 'org.apache.spark.sql.json.DefaultSource'
+ *
+ * A new instance of this class with be instantiated each time a DDL call is made.
+ */
+@DeveloperApi
+trait SchemaRelationProvider {
+  /**
+   * Returns a new base relation with the given parameters and user defined schema.
+   * Note: the parameters' keywords are case insensitive and this insensitivity is enforced
+   * by the Map that is passed to the function.
+   */
+  def createRelation(
+      sqlContext: SQLContext,
+      parameters: Map[String, String],
+      schema: StructType): BaseRelation
+}
+
 /**
  * ::DeveloperApi::
  * Represents a collection of tuples with a known schema.  Classes that extend BaseRelation must